I'm think what is occurring is described in the section titled Selecting the Best Threshold Value in the C6000 compiler manual. I'll quote the most relevant bit ...
If the symbol information is not known during compile time, the linker will ensure that the placement of data sections will allow legal accessing beyond the boundaries of the data sections. The linker does this by simply padding the start and end of the memory range(s) where the data sections are placed.
I'm pretty sure that, due to using -mh=auto, the linker is adding padding to every section that may contain data, including .stack and icbPtrSect.
Thanks and regards,
-George